Robert Peston

I’ve been sent a recording of a presentation made on Tuesday by the great champion of Brexit, Boris Johnson, over breakfast in Amsterdam. He was talking to “chief risk officers” of financial firms at an event called RiskMinds International, that was sponsored by, among others, the huge accounting firm PWC and the management consultancy McKinsey. Days before that big vote on Theresa May’s version of Brexit, which Johnson passionately opposes, he talks about the importance of politicians, like his hero Churchill, taking a stand against the establishment and “gambling” – making a “giant bet” – to do the right thing.

Theresa May (and I) are just back from Argentina. And she is about to enter the most important week of her political life and the most important week in this country’s political and constitutional history for decades. It starts tomorrow with the publication of a summary of the legal advice on the PM’s Brexit plan - which will expose an irreconcilable contradiction at the heart of the so-called backstop to keep open the border on the island of Ireland. On the one hand, if the UK were to trigger the backstop at the end of 2020, which would effectively take us into the EU’s customs union, the UK would never have the unilateral right to leave it.

The Prime Minister might have been a bit too clever when attacking Corbyn’s and Labour’s opposition to her Brexit deal. Some four hours in to her 14 hour flight to the G20 leading nations’ summit in Argentina, she told journalists: “What they are doing is advocating rejecting the deal we negotiated with the European Union without having any proper alternative to it. “They say they don’t want ‘no-deal’ but by appearing to reject a temporary backstop they are effectively advocating no-deal, because without a backstop there is no deal”. So she is accusing Labour of ushering in the kind of economic no-deal calamity – a devastating recession that would see the income of the U.K.

We've all been focussing on the crisis that would ensue if – as expected – the PM loses the meaningful vote on her Brexit deal ‪on 11 December‬. But just for a moment think about the implications if she wins, because they too would be momentous. To state the obvious, we'd be out of the EU on terms that are semi-blind – we wouldn't know our long-term destination. But we would be out. And she, the PM, would rein supreme. She would have crushed her opponents, who would have lost all hope of political advancement or favour. And having delivered Brexit against the odds, she could be pretty confident in staying PM for as long as she wanted, perhaps well beyond the next election – and the election itself would be off the cards till 2022.

The publication by the Treasury of its forecasts of the economic impact of Theresa May's Brexit deal, versus no-deal and staying in the EU, has been keenly awaited. But it turns out that what we will read, probably on Wednesday, will be almost irrelevant. Because what the Treasury has modelled is not the deal actually struck on Sunday by Theresa May, but her Chequers plan. And, as you will be keenly aware, the rest of the EU has rejected her Chequers combination of the UK staying in the single market for goods and the dual-tariff customs territory the Facilitated Customs Arrangement.

First things first. There has been a widespread misunderstanding of why Angela Merkel made it known yesterday that if the Brexit deal – Withdrawal Agreement and Political Declaration – wasn't done and dusted by today, she would not be bothering to turn up in Brussels to formally ratify it on Sunday. Her conspicuous intervention was not aimed at putting pressure on Theresa May to be more emollient in the last leg of negotiations. The German Chancellor was in fact asking the likes of the Spanish premier Pedro Sanchez to stop misbehaving and causing unnecessary bother (Sanchez has been playing to a domestic audience by saying he would block any agreement that deprived him of a veto on the future of Gibraltar). "The chancellor was doing the PM a favour" said an official.

This is a PM who has shown herself capable of surviving extraordinary personal humiliations. But to lose two two Brexit secretaries - David and now Raab - in fairly rapid succession is a set back of a different magnitude. They were supposed to be in charge of Brexit. And yet both have resigned rather than being associated with a Brexit plan they hate and squarely lay at her door. Raab’s resignation letter says she has agreed to be shackled by the EU to an extent that 'no democratic nation' has ever allowed. So she is now personally and inextricably linked to a Brexit plan - the most important British initiative in modern times - which parliament is set to reject.

On the controversial - some would say "life or death" - question of how to keep open the border between Northern Ireland and the Republic of Ireland, the backstop, this is what I am told has been agreed. It is what's described in Brussels as the "swimming pool" approach - in other words it has a shallow end and a deep end, when it comes to measures aimed at making sure trade is completely frictionless between NI and the ROI, and fairly frictionless between Great Britain and the EU27. GB would be in the shallow end, NI in the deep. Or to be more precise, the whole of the UK would stay in the customs union if a long-term trading relationship between the UK and EU isn't negotiated and implemented by the end of 2020 - which no one (with the possible exception of the PM) expects it to be.

Pity Olly Robbins and Sabine Weyand who are as we speak negotiating a Brexit deal for their respective bosses, Theresa May and the EU27. Because following the resignation of Jo Johnson, it is now clearer than ever that the deal they will probably agree this weekend, to be put to the Cabinet on Monday (or at the very latest on Tuesday), will be rejected by Parliament. They are straining every one of their intellectual sinews to reach an agreement that is almost impossible given the ideological gulf between them on how to keep open the border between Northern Ireland and the Republic of Ireland. And when they succeed through the application of sophistry on a Herculean scale, what then?

The flurry of overnight speculation that a deal had been done to guarantee post-Brexit access for the City to the EU was all a bit odd. It's true that a few weeks ago, the Treasury over the course of a couple of days successfully negotiated some "high level principles" for what the future access relationship might be for UK-based banks and other financial institutions to the EU's single market. But this is a million miles from a deal – which would not and could not be negotiated in its practical detail for months and even possibly years.

There is an operation in progress by Tory Brexiters to persuade fellow backbenchers to write to Graham Brady, chair of the 1922 backbench committee, calling for a vote of no confidence in Theresa May as leader of their party. This is what one of them told me: 'I’m campaigning myself. We need 60-70 letters, not 48... I know people who are putting letters in today. I think we are the closest ever to her going and I think, thank God, this could be it.' The reference to 48 letters is the threshold for triggering the vote. But this MP wants a comfortable margin above that, so that the PM can see that a sizeable number of her colleagues want her to go. This is not an exquisitely centralised and coordinated campaign against her.

Hello from Brussels and the EU Council that promised a Brexit breakthrough and delivered nothing. So on the basis of conversations with well placed sources, this is how I think the Brexit talks are placed (WARNING: if you are fearful of a no-deal Brexit, or are of a nervous disposition, stop reading now). Forget about having any clue when we leave about the nature and structure of the UK’s future trading relationship with the EU. The government heads of the EU27 have rejected Chequers. Wholesale. And they regard it as far too late to put in place the building blocks of that future relationship before we leave on 29 March 2019. So any Political Declaration on the future relationship will be waffly, vague and general. It will be what so many MPs detest: a blind Brexit.

I am very sorry to do this to you, but it turns out that the incendiary extension to the UK’s period as a non-voting member of the EU – the mooted extra months in “transition” – isn’t really an extension. It is an “option” on an extension, the right to have an extension. Yes you guessed it: what we are talking about is another flipping backstop. And yes I too am losing the will to live as these Brexit talks descend from giant geopolitics to nightmarish logical puzzles. Here is the background. The EU cannot – it insists – agree our preferred version of the Northern Ireland backstop as part of the Article 50 Withdrawal Agreement.

I've been asking officials and ministers for the prime minister's cunning plan to solve the seemingly impossible Brexit puzzle - of proving to her Brexiters that the Northern Ireland backstop plan would be temporary while avoiding any specified fixed termination date (because a backstop with a fixed termination date cannot, by definition, be a backstop; to mix metaphors, it would be a cliff edge). Here is what I've been told: 'The backstop cannot be limited by a fixed date' said a member of the government (telling you and me what the EU insists upon, but what Tory Brexiter MPs see as heresy). 'But it might be capable of limitation by reference to a formula or a test to establish redundancy.' Hmmm. A formula. Intriguing.

Maybe I was wrong (words I probably don’t say enough). I thought the DUP would be fairly pragmatic about the terms of the 'backstop' designed to keep open the border between Northern Ireland and the Republic of Ireland till a permanent solution was found (stop smirking). So when I learned that the draft backstop deal agreed on Tuesday by UK and EU officials contained 'only' a requirement for additional physical checks in and around the Irish Sea on agriculture and food, I thought the DUP could probably live with that. How so? Well there are already such checks. And what is being proposed is simply an increase from 10 per cent to 100 per cent of checks on livestock and foods to verify them as healthy and conforming to EU standards.

I am hearing that the PM’s Brexit advisor Olly Robbins has made meaningful progress in talks with the EU’s negotiator Michel Barnier on that contentious “backstop”, or insurance policy to keep open the border between Northern Ireland and the Republic of Ireland pending agreement on a permanent long-term trading relationship that achieves the same. Depending on who I talk with, there’s either been a breakthrough or things are moving in the right direction. My sense therefore is that it would be premature to crack open the champagne bottles, but maybe a half-bottle should be on ice.

Theresa May would never sell herself as a great orator. But that was a good speech, perhaps the most significant of her lifetime in Tory politics. It was an address that achieved three things. It confirmed that she is sticking to her Chequers Brexit strategy - not that she even once uttered the controversial 'C' word. And she tried to acquire some wiggle room from sceptical members, so that she can offer the rest of the EU compromises on both the future trading relationship with them and the insurance policy, or backstop, to keep the Ireland border open. Second, it planted the Tories in the centre of politics, with a pledge to end austerity and loosen the borrowing cap on local councils for housebuilding.

There is widespread, fevered speculation that the prime minister will move away from her Chequers plan for a future relationship with the EU at this afternoon's Cabinet, under intense pressure from her ministerial colleagues. Having now spoken to several ministers, I am clear that she will stand firm on Chequers, and there probably won't be a concerted and coordinated effort TODAY from the Brexiters in her team - Gove, Fox, Leadsom, Mordaunt and McVey - to shift her towards the kind of free trade proposal preferred by Boris Johnson, David Davis, Jacob Rees-Mogg and the European Research Group.